Constant intensity light source for fiber optic testing

Claim 1

A supply circuit for a stable fiber optic light comprising; a power circuit responsive to a control signal and comprising a power source, a comparing and amplifying means for comparing the voltage of the power source with the voltage of a stabilized electrical control signal and for emitting, in response thereto, an amplified electrical signal proportional to the difference between the power source voltage and the stabilized electrical control signal voltage, and a transistor circuit to increase or decrease the current from the power source in response to the amplified electrical signal from the comparing and amplifying means; and a stable light-emitting system comprising a semi-conductor light source for generating optical power in proportion to the signal from the power circuit, and a feedback control system comprising means for determining a signal characteristic of the optical power generated by the semi-conductor light source and in response thereto, generating the electrical control signal for control of the power circuit as aforesaid; wherein the feedback control system comprises; a mixing rod for conveyance of the optical power, a splitter for receiving the optical power from the mixing rod and for splitting the power into at least a fiber optic product portion and a fiber optic control portion, and a detector for sensing the fiber optic control portion and for producing, in response thereto, the electrical control signal for control of the power circuit.